The major objectives of this research are to characterize dopamine, adrenergic and opiate receptors involved in neuroendocrine regulation of LH and prolactin at both the level of the anterior pituitary and median eminence. Dopamine receptors in the anterior pituitary will be solubilized and purified. Antibodies will be generaged to dopamine receptor in rabbits and by the monoclonal antibody techniques. The antibodies as well as derivatized dopaminergic antagonist linked to ferritin will be used to label dopamine receptor in the anterior pituitary and hypothalamus at the light and electron microscopic levels. Modulation, distribution, aggregation and internalization of anterior pituitary dopamine receptors will also be studied. Stable hybrid cell lines will be established which secrete prolactin and express cyclase or non-cyclase dependent dopamine receptors or beta-adrenergic recptors. Dispersed anterior pituitary cells will be maintained in long term cultures on extracellular matrix. These cultures will be used to study the role of dopamine in regulating responsiveness of mammotrophs to the suppression of prolactin release. Responsiveness will be correlated with dopamine receptor number and affinity in whol cell radioligand assays.